3,3-Dimethyl-1-butyne → 5-(3,3-Dimethyl-but-1-ynyl)-thiophene-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A 350 mL heavy wall round bottom flask was charged with TEA (33.7 mL, 24 mmol, 5.0 equiv), BINAP (3.0 g, 4.83 mmol, 0.1 equiv), 5-bromo-thiophene-2-carboxylic acid (48.3 mmol, 1.0 equiv), CuI (0.184 g, 0.97 mmol, 0.02 equiv), Pd2dba3 (2.2 g, 2.4 mmol, 0.05 equiv) and DMF (40.0 mL). The flask was flushed with N2 and to the mixture was added t-butyl acetylene (15.8 g, 193 mmol, 4.0 equiv). The mixture was sealed and stirred at 70° C. for 48 hours. After cooled at room temperature, the reaction mixture was filtered and the filtrate was concentrated under vacuum. The residue was acidified with 3.0 N HCl until pH=4. The aqueous layer was extracted with EtOAc. The organic layer was washed with brine, dried over Na2SO4 and concentrated. The residue was purified by silical gel, EtOAc/heptane 5% to EtOAc/heptane 30% with 2% of AcOH to give product 6.5 g (yield 65%).

Provenance & Evidence